21066910920 has 320 divisors, whose sum is σ = 77943824640. Its totient is φ = 5060966400.

The previous prime is 21066910903. The next prime is 21066910937. The reversal of 21066910920 is 2901966012.

It is an interprime number because it is at equal distance from previous prime (21066910903) and next prime (21066910937).

It is a super-2 number, since 2×21066910920² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 4024705 + ... + 4029935.

It is an arithmetic number, because the mean of its divisors is an integer number (243574452).

Almost surely, 2^21066910920 is an apocalyptic number.

21066910920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21066910920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38971912320).

21066910920 is an abundant number, since it is smaller than the sum of its proper divisors (56876913720).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21066910920 is a wasteful number, since it uses less digits than its factorization.

21066910920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5378 (or 5365 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The spelling of 21066910920 in words is "twenty-one billion, sixty-six million, nine hundred ten thousand, nine hundred twenty".